This proposal will provide the faculty of the Massachusetts Institute of Technology a resource to support their efforts in the utilization of laboratory animals for research and teaching. Over 105 principal investigators use approximately 100,000 animals annually at the Institute. We also provide diagnostic services for 13 Boston area biomedical facilities with an accumulative daily census of 81,500 animals. The research animal diagnostic laboratory is adequately staffed and equipped to provide diagnostic services in hematology, microbiology, parasitology, clinical chemistry, virology, histology and gross and microscopic pathology to support the animal disease control program of the Institute. In addition the diagnostic laboratory will support research activities in the study of diseases of laboratory animals and will continue to assist in the recognition and development of animal analogs to human disease. Further the laboratory staff will continue in and facilitate expansion of the present teaching programs of the Division of Comparative Medicine, for graduate, undergraduate and summer veterinary students. It is essential to the overall research program that diagnostic laboratories and veterinary support be available at the Institute.